1. Field of the Invention
The present invention relates to a transmission control method for use in arranging a local area network (LAN) among a plurality of equipment by transmitting various information via radio waves, for example, and a transmission apparatus to which this transmission control method is applied.
2. Description of the Related Art
Heretofore, there has been arranged a local area network capable of transmitting data handled by a plurality of equipment among a variety of video equipment and a plurality of equipment such as a personal computer and its peripheral devices in a relatively narrow range such as homes, offices and so on. In this case, instead of directly connecting respective equipment by signal lines, transmission and reception apparatus (radio transmission apparatus) for transmitting and receiving radio signals are connected to respective equipment and data can be transmitted via radio waves.
When the local area network is configured by radio wave transmission, respective equipment need not be directly connected by signal lines or the like, and hence the system arrangement can be simplified.
When the local area network is realized by preparing a plurality of radio transmission apparatus, if signals are simultaneously transmitted from a plurality of transmission apparatus, there is then the possibility that a transmission error will occur. Therefore, a communication among respective transmission apparatus within the network should be access-controlled by some method.
As an access control method, in a small-scale radio network, for example, there is known a method in which a communication among respective transmission apparatus (nodes) within the network is managed by a transmission apparatus (root node) at the star-connection central portion in a centralized fashion.
In a centralized transmission line management based on the root node, initially, the root node determines a fixed frequency (channel) in such a manner that an interference may not occur in all nodes around the root node. Then, slots are allocated to the frequency and a communication between the nodes is executed in the respective allocated slots.
However, if such fixed slot allocation had been executed, a number of frequency bands (a plurality of channels) for preventing an interference with other systems would have been prepared although they are not used in actual transmission. Naturally, when a transmission of wide band information is assumed, it is inevitable that transmission bands as much as several times the frequency bands should be prepared.
According to the above-mentioned arrangement, it is difficult to effectively utilize limited frequency resources. In addition, it is difficult to cope with the case in which even the channel obtained by the initialization is disturbed by another system when information is transmitted or the case in which such channel disturbs the other system.
As a method of solving such problems, it is considered to design a transmission line by a CDMA (code division multiplexed access) system which is difficult to be affected by interference disturbance around the transmission line. However, since this CDMA system is a technology for diffusing a signal upon transmission, if transmitted information is wide-band information, then a huge number of transmission bands are required.
In the conventional network transmission, there is generally used a method in which information is constantly transmitted under control of the root node. Here, in the radio network, if transmission that can be directly effected without the root node is directly effected between the nodes, then the radio resources may be utilized effectively. However, since it is general that the transmission between the nodes is controlled by the management of the radio resources based on the root node, if slots that are substantially close to the maximum transmission capacity are allocated at one portion of the network, for example, then substantially no slots can be allocated to the transmission between other nodes.
Further, in the slot transmission, when a control method does not return transmission status information, a judged result indicating the failure of transmission should be reported by another communication means. To report such judged result, a huge control system is required to allocate slots again by using an asynchronous communication.
It is an object of the present invention to provide a transmission control method and a transmission apparatus in which a transmission band can be utilized effectively by simple control.
According to an aspect of the present invention, there is provided a transmission method which is comprised of the steps of determining a management data transmission area and a data transmission area within a frame period, disposing a plurality of slots in the data transmission area and transmitting slot using situation data in each communication station or control station of the data transmission area in the management data transmission area.
According to the transmission method of the present invention, by a communication using the management data transmission area, each slot using situation within the data transmission area can be understood, collected and managed by the control station, for example.
According to another aspect of the present invention, there is provided a transmission apparatus which is comprised of a timing setting means for setting a frame period based on a predetermined synchronizing signal, setting a management data transmission area and a data transmission area within the frame period and further setting a plurality of slots in the data transmission area, a transmitting means for transmitting each slot using situation data of its own station in the management data transmission area and transmitting data in the data transmission area slot allocated by a control apparatus, and a receiving means for receiving data in the data transmission area slot allocated by the control apparatus.
According to the transmission apparatus of the present invention, based on the data received in the management data transmission area within the frame period, each slot using situation of its own station can be transmitted to the control apparatus side, and a control based on each slot using situation data becomes possible.